The subject matter disclosed herein relates to valves and valve diagnostics with particular discussion below that describes techniques to improve efficiency of data collection for diagnostic analysis of a valve assembly on a process line.
Industrial factories and like facilities operate process lines that may include many varieties of flow controls. Examples of these flow controls include pneumatic and electronic valve assemblies (also “control valves”) that regulate a flow of process fluid (e.g., gas and liquid). In conventional configurations, these valve assemblies have a number of components that work together to regulate flow of process fluid through the valve assembly. These components include a stem, a plug, a seat, and an actuator that couples with the stem to change the position of the plug relative to the seat. The components can also include various linkages and springs that ensure proper movement, e.g., of the stem and/or the plug. In some constructions, the valve assembly incorporates a valve positioner with electrical and/or electro-pneumatic components. During operation, the valve positioner instructs the actuator to change the position of the plug relative to the seat. Often, the valve positioner issues the instructions in response to control signals from a controller that is part of a process control system (also “distributed control system” or “DCS”). The instructions are part of management functions in the DCS that can, inter alia, cause the valve assemblies to operate in a manner that achieves the process parameters set out for the process line.
Facilities and operators often allow techniques that collect data from the valve assemblies to diagnose issues that could be detrimental to operation of the process lines. These techniques typically do not interrupt operation of the valve assemblies. The data may include data that relates to operative variables including setpoint, pressure, position, and like information. This data is available via the DCS, the valve positioner, and/or other components in the facility. However, although the data that reflects the operating variables is helpful to diagnose problems with the valves, processes are meant to minimize variations in operating variables to maintain stability and predictability of the process output. The stability of the process requires techniques to continuously collect data from the valve assemblies to increase the likelihood that the data collected will reveal observable movement in the components of valve assembly. This movement is critical for proper diagnosis of the device using many online diagnostics and related predictive maintenance techniques. Unfortunately, the vast number of valve assemblies in use in the facility, as well as limits on bandwidth on the systems/networks to gather data, can frustrate the process of data collection. These limitations can prevent diagnostic techniques to capture enough data to identify movement or other activities of the valve assemblies, let alone to observe problems with one or more valves assemblies on the process line.